Systems for providing image signals typically include a camera positioned to be focused upon an object and constructed for providing image signals representing an image of the object. Typically, these systems include apparatus for monitoring the image signals and for varying the focus of the camera to provide a focused image signal. However, in such systems, it is not possible to obtain a focused image if any significant relative motion exists between the image and the camera while the image is being obtained.
To eliminate the effect of relative motion between the camera and the object, prior art systems typically require an unacceptably long waiting period, or settling time, for all relative motion between the camera and the object to stop before the image is obtained. Accordingly, it is desirable to provide a camera system capable of obtaining focussed image signals wherein a camera system moves in relation to the object.
Further, even when the object or the camera is not in relative motion, the above-referenced camera systems require an unacceptably long time to focus the camera. This is because the above-described focusing mechanism requires a focused signal to be received before the proper focusing position of the camera can be determined. Accordingly, the focus of the camera must be varied until an acceptably focused image signal is received, before the desired image signal can be obtained. This procedure is unacceptable and tedious. The focus time of these systems is further increased since changing the focus causes vibration that must be stopped before the desired image signals can be obtained. It is desirable, therefore, to provide a camera system capable of determining the proper focus position of the camera without the necessity of receiving focused image signals.
Several prior art systems have attempted to reduce the time required to focus a camera by obtaining a preliminary image. These systems then use data processing methods to determine whether the preliminary image was in focus and, if not, to determine the proper focus of the image. However, such systems still require a settling time before the preliminary image can be obtained. Further, these systems require that the entire image be obtained before a determination of focus can be made. Also, if the preliminary image is determined to be out of focus, the entire process must be repeated, before the camera is moved, to obtain the in-focus image.
Still further, obtaining image signals representing a plurality of objects with the above-referenced camera system is time-consuming because each object must be focused and the focused image signals must be provided before an image of the next object can be taken. The time wasted focusing upon a single object and waiting for relative motion to stop is multiplied by the number of objects for which image signals are desired. Therefore, these systems become even more unacceptable as the number of objects increases.
Accordingly, it is it is an object of this invention to provide a camera system wherein a large number of image signals can be obtained rapidly. It is a further object of the invention to capture an image in every video frame.
One aspect of the invention of particular interest is a motion control apparatus that operates to send a scan synchronization signal to image capture apparatus, where the scan synchronization signal indicates that the motion control apparatus will position a slide at a selected set of coordinates for scanning within a precisely specified time interval, where the motion control apparatus provides the scan synchronization signal prior to the motion control apparatus actually moving the slide into position.
Other objects, features and advantages of the present invention will become apparent to those skilled in the art through the description of the preferred embodiment, claims and drawings herein wherein like numerals refer to like elements.